School-slate



N.Du13RUL.V School-Slate..

No. 225,215. Patented Mar. 9, 1880.

.vc-IL www? UNITED STATES PATENT OFFICE.

NAPOLEON DU BRUL, OF CINCINNATI, OHIO.

SCHOOL-SLATE.

`'SPECIFICATION forming part of Letters Patent No. 225,215, dated March 9, 18.80.

Application filed December B, 1879.

or coupling device for those school-slates which consist of two leaves or tablets so connected as to be capable of being folded with equal ease either forward or backward.

My improved coupling device consists, essentially, of a slender metallic rod or wire, which, in connection with suitably grooved and notched slate-frames, serves as a reversible hinge. For this purpose said Wire is bent near each end, first at right angles to the central port-ion, and then bent back to its former direction, thus forming a bayonet-shaped hinge at each end, the middle portion of the wire bcing parallel to the extremities, as hereinafter described. The thus bent wire having been inserted in the grooves prepared for it is secured in place by the closure of the grooves by means or glued wooden strips or by metallic staples, or both.

In the accompanying drawings, Figure l is a perspective view of a folding school-slate embodying 'my invention. Fig. 2 is a back-edge view of the two frames, and of the couplingwire and the cleats detached. sents a modification of my improvement.

A and A' represent the two leaves of a reversible slate whose frames have the customary half-round or convex edges. rIhe Opposing frame-edges are grooved longitudinally at a a', and notched transversely at a, for the recep- Fig. 3 repretion of a slender cylindrical rod or'wire, B, which is bent near its extremities, b b', into the form of a bayonet-like hinge by rst bending the wire at right an gles to the centralportion, and then bending them so that they shall extend in their former direction, said hinge being out of line but parallel with the middle portion, b, of the wire. The thus bent wire having been inserted in the grooves a d is secured in place by the insertion of `glued wooden strips or cleats C, or by staples D, or by both staples and cleats, if desired.

The piece B may be easily and cheaply formed out of round wire, of brass, iron, or other suitable metal, by aV single Operation of suitable dies. 1

The above-described illustration 0E my invention lmay be changed in non-essential particulars. For example, the coupling-wire may have a greater number of bends, as shown in Fig. 3. The longitudinal grooves may be formed in the face instead of in the edge of i the, slate-frame.

I claim as new and as my inventiony The double reversible school-slate consisting of a pair of round-edged and longitudinallygrooved and transversely-notehedleaves, A' a a, and the rod or wire B, bent or formed at the extremities b b into the bayonet-like form shown, the whole being arranged, secured, and adapted to operate substantially as set forth.

In testimony of which invention I hereunto set my hand.

NAPOLEON DU BRUL. Attest:

GEO. H. KNIGHT, WALTER KNIGHT. 

